The present invention relates to the field of angioplasty. In particular, the present invention relates to a guide catheter system for guiding an angioplasty balloon catheter into a patient's arterial system.
Angioplasty has gained wide acceptance in recent years as an efficient and effective method for treating certain types of vascular diseases. In particular, angioplasty is widely used for expanding a constricted area or stenosis in coronary arteries. It is also used for treatment of stenoses in other parts of the vascular system as well.
The most widely used form of angioplasty makes use of an angioplasty balloon catheter which has an inflatable balloon at its distal end. Using fluoroscopy, the physician guides the angioplasty balloon catheter through the vascular system until the balloon is positioned across the stenosis. The balloon is then inflated by supplying fluid under pressure through an inflation lumen connected to the balloon. The inflation of the balloon imparts a stretching force to the stenosis and artery wall to re-establish an acceptable blood flow through the artery.
An angioplasty balloon catheter is normally introduced and directed through a patient's vascular system by a guide catheter. Guide catheters generally comprise a stiff shaft to provide support for the angioplasty balloon catheter as it is advanced through a patient's vascular system. The dimension of the guide catheter generally coincides with the insertion artery of a patient, and is generally large enough so that the angioplasty balloon catheter may easily insert therethrough to the coronary ostium. However, the dimension of the guide catheter is generally larger than the smaller dimension coronary arteries of the heart and thus its insertion through these arteries is restricted. In addition, the guide catheter is too stiff to negotiate the tortuous path of the coronary arteries. Thus, when a stenosis is located within these smaller dimension arteries, it is difficult for the guide catheter to provide assistance directly thereto.
U.S. Pat. No. 4,581,017 suggests a guide catheter arrangement capable of accessing the smaller coronary arteries. Specifically, U.S. Pat. No. 4,581,017 suggests that a smaller diameter guide catheter section extend from the primary guide catheter section for insertion into the coronary arteries.
There are generally two types of angioplasty dilatation balloon catheters. Both types incorporate a guide wire to direct and assist the insertion of the angioplasty balloon catheter. The first type is an "over-the-wire" type dilatation catheter. In this type catheter a separate guide wire lumen is provided through which the guide wire is fed and maintained along the length of the angioplasty balloon catheter. This arrangement permits the independent insertion and retraction of the guide wire with respect to the inflatable balloon at the distal end of the angioplasty catheter.
The advantage of the over-the-wire type catheter is that it allows the doctor to establish, by the guide wire, the position of the obstruction or lesion independent of the position of the angioplasty catheter. This advantage is important when a catheter exchange is necessary (e.g., where a larger or smaller balloon is substituted for the balloon originally inserted). The need to substitute a larger or smaller balloon becomes apparent after the stenosis is located and its configuration is determined. If a catheter exchange is necessary, the location or position of the lesion must be reestablished after the original angioplasty balloon catheter is withdrawn. Thus, the reinsertion process requires the same delicate procedure as the original insertion if the path to the stenosis must be reestablished. It is generally preferred to have an angioplasty balloon catheter system which can mark or remember the location of the lesion so that a different angioplasty balloon catheter can be easily substituted for the one originally inserted.
The independent operation of the guide wire of the over-the-wire type dilatation catheter provides an easy means for establishing and recording the location of the obstruction. The angioplasty balloon catheter may be independently withdrawn leaving the guide wire to mark the position of the lesion. Thus, an alternate angioplasty balloon catheter may be inserted and positioned over the guide wire marking the position of the lesion. Although the over-the-wire type dilatation catheter provides an advantage for a catheter exchange, it necessarily has a larger profile because of the necessity of having a guide wire lumen which may restrict its passage through the smaller coronary arteries of the heart.
The other type of dilatation catheter is a "fixed-wire" dilatation catheter. The guide wire of the fixed-wire dilatation catheter is operatively associated with the angioplasty balloon catheter and moves therewith. The profile required for a fixed-wire catheter is typically smaller than that required for an over-the-wire type dilatation catheter because the need for a separate guide wire lumen is eliminated. Thus, the fixed-wire dilatation catheter may be inserted further through the smaller coronary arteries of the heart to reach the stenosis or lesion. However, there is a significant disadvantage associated with the concurrent movement of the guide wire and the angioplasty balloon catheter of a fixed wire dilatation catheter. If it is necessary to perform a catheter exchange in order to properly dilate the lesion, the guide wire is withdrawn in combination with the angioplasty balloon catheter leaving nothing behind to mark or remember the position of the lesion in the artery.
There is, therefore, a continuing need to provide a dilatation catheter system that is capable of marking and remembering the position of the lesion within the smaller coronary arteries associated with the heart for an effective catheter exchange.